Synthetic turf having cooling layer

ABSTRACT

The present invention describes a synthetic turf having super absorbent materials in order to keep the synthetic turf cooler than conventional synthetic turfs. The present invention also provides for synthetic turf infill cooling particles comprising a layer of water-absorbing material coating a foundation comprising a core substrate. In one embodiment, the cooling particle is comprised of a core particle or substrate, which is coated with a water-absorbing material. In one embodiment, the water-absorbing material is a super absorbent polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part to and claims priorityto nonprovisional U.S. patent application Ser. No. 12/646,250 filed Dec.23, 2009, to provisional U.S. Patent Application No. 61/150,905 filedFeb. 9, 2009 and to provisional U.S. Patent Application No. 61/251,579filed Oct. 14, 2009.

BACKGROUND ON THE INVENTION

1. Field of the Invention

The present invention relates generally to synthetic turf forlandscaping, roofing, and athletic fields, and more particularly tosynthetic turf having a cooling layer to substantially dissipate heatbuildup common with synthetic turf. The invention also relates to

2. Description of the Related Art

Traditionally, athletic fields, as well as landscaped areas for homesand businesses, are covered with a natural grass covering. The naturalgrass is advantageous for cushioning and ability to quickly recover fromabuse from weather, people, or both.

In recent years, however, many athletic fields have been converted fromnatural grass to synthetic turf systems. The reasons for converting tosynthetic turf is most often linked to the high costs and time relatedto maintaining natural grass. Further, natural grass may have problemsgrowing in certain environmental and man-made conditions, such as forexample, desert regions, spaces shaded by buildings, domed fields andhigh traffic areas. In areas where the natural grass cannot growproperly or adequately, injuries can result from inadequate footing. Inaddition, poorly growing natural grass is typically not aestheticallypleasing.

Synthetic turf systems have improved over the years to appear more likenatural grass coverings. Other improvements have been made to give morecushioning and elasticity to the synthetic turf to make it more equal tothe advantages of natural grass turf.

However, a primary disadvantage of synthetic turf systems still exists.In particular, most synthetic turf systems are comprised primarily ofplastics, such as, for example, polyolefin. Such plastics absorb,retain, and radiate heat that can increase the temperature on a field toa potentially fatal level. Even the American Academy of Pediatrics hasidentified infill artificial turf as contributing to elevating aperson's core body temperature, thereby leading to heat related injuriessuch as, for example, heat cramps, heat exhaustion and heat stroke.

It has been found that naked synthetic turf systems, that is, synthetictuft coverings without infill material, such as, for example, sand andrubber, can reach temperatures of 140° F. or greater. Natural grasscoverings measure about 85° F. under similar circumstances. Essentially,the materials comprising most synthetic turf systems absorb heat fromthe sun and retain the heat in the ground to a much greater extent thannatural grass coverings. Sand and rubber granules have been used asinfill to increase footing and playability of athletic fields, but suchinfill materials do not mitigate heating issues of infill artificialtuft. In fact, rubber infill may actually contribute to increasing thetemperature of the artificial turf. Lighter colored rubber granules andwetting the sand infill have been proposed as a mean by which to try anddecrease the overall temperature of the synthetic turf system, however,such proposals tend to cool the artificial turf for a very limited, timeand only at an almost insignificant temperature change.

In addition to being related to increasing heat-related injuries,synthetic turf systems also are associated with heat pollution. Themassive amount of heat rising from urban areas is increasingly beinglinked to both a delay and stimulation of precipitation. Some areas areexperiencing a noticeable decrease in much needed rain and snow, whileother areas are seeing an increase. There is strong support that heatand pollution from urban areas effects climate in an alarming way;primarily by redistributing water in an undesired fashion.

As such, governments are considering and implementing environmentalstandards to limit the heat generated from urban areas. Some of thestandards call for increased natural green spaces and fewer areas ofblacktop and concrete, that is, artificial spaces that buildup and giveoff great amounts of heat pollution. Typical synthetic turf systems canbehave very much like blacktop When it comes to heat pollution.

Attempts have been made to decrease the temperature of synthetic turfsystems. Attempts to cool synthetic tuft coverings include watering downthe coverings. However the water quickly evaporates. More recentattempts include mechanical means in which a series of cooling pipes areconstructed under the synthetic turf systems. However, such mechanicalmeans is expensive and would require removing currently laid syntheticturf systems.

Ceramic beads having about 50% porosity have been combined with sand andrubber granules to supplement mechanical cooling systems as a means forcooling artificial turf coverings. However, the ceramic beads are unableto hold enough water to significantly decrease the temperature of thesynthetic turf system. Lighter colored rubber has also been proposed asa means for decreasing the temperature of the synthetic turf system, butalso does not lend to significantly decreasing the overall temperatureof the synthetic turf system.

Other means of cooling synthetic turfs are set forth in U.S. Pat. No.5,153,553 to Tetrault where super absorbent polymers are included ininfill. Although such means is successful in decreasing synthetic turftemperatures, the super absorbent polymers in such circumstances riskbeing separated from the associated synthetic turf due to weather andwear and tear.

Thus, what is needed is an economically affordable means for coolingsynthetic turf systems over a significant period of time without concernof loss of cooling materials that are also environmentally friendly.

SUMMARY

The various exemplary embodiments of the present invention include asynthetic turf system. The synthetic turf system is comprised of afoundation, a plurality of grass-like filaments, and at least onecooling mat. The foundation is selected from one or more of bare ground,stone, gravel, sand, asphalt, cement, and rubber. The plurality ofgrass-like filaments is attached to a backing layer such that thebacking layer is substantially adjacent to the topside of the foundationand the plurality of grass-like filaments extend substantially upwardfrom the backing layer. The at least one cooling mat is comprised of oneor more layers wherein at least one of the layers is comprised of superabsorbent polymers.

The various exemplary embodiments of the present invention furtherinclude a method of cooling a synthetic turf system. The synthetic turfsystem is comprised of a foundation, wherein the foundation is selectedfrom one or more of bare ground, stone, gravel, sand, asphalt, cement,and rubber; and a plurality of grass-like filaments attached to abacking layer such that the backing layer is substantially adjacent tothe topside of the foundation and the plurality of grass-like filamentsextend substantially upward from the backing layer. The method includesthe steps of introducing one or more acrylic polymers admixed with amonomer that causes cross-linking the polymers to form one or moresuperabsorbent polymer intermeshed and crosslinked within the coolingmat such that the SAP cannot be separated from the mat. The exemplaryembodiments of the present invention further include synthetic turfsystem comprised of a foundation and a plurality of grass-likefilaments. The foundation is selected from one or more of bare ground,stone, gravel, sand., asphalt, cement, and rubber. The plurality ofgrass-like filaments are attached to at least one cooling mat comprisedof one or more layers such that at least one of the layers is comprisedof super absorbent polymers and is substantially adjacent to the topsideof the foundation and the plurality of grass-like filaments extendsubstantially upward from the at least one cooling mat.

BRIEF DESCRIPTION OF THE DRAWINGS

The various exemplary embodiments of the present invention, which willbecome more apparent as the description proceeds, are described in thefollowing detailed description in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an illustrated representation of an exemplary embodiment ofthe present invention.

FIG. 2 is an illustration representing another exemplary embodiment ofthe present invention in which the cooling mat is positioned above abacking layer.

FIG. 3 is an illustration representing an exemplary embodiment of thepresent invention in which a plurality of grass-like filaments aretufted to the cooling mat without a backing layer.

FIG. 4 is an illustration representing an exemplary embodiment of thepresent invention in which resilient or nonresilient core particle iscoated with a layer of superabsorbent polymer.

FIG. 5 is an illustration representing an exemplary embodiment of thepresent invention in which resilient or nonresilient core particle iscoated with a layer of binder that promotes adhesion of the coating ofsuperabsorbent polymer.

FIG. 6 is an illustration representing an exemplary embodiment of thepresent invention in which various composition layers of superabsorbentpolymer-coated and non-coated resilient core particles, nonresilientcore particles or mixtures thereof are coated with superabsorbentpolymer and used as infill for an artificial ground substrate.

FIG. 7 is an illustration representing a cross-section of the infillused in an exemplary embodiment of the present invention showing variouslayers of superabsorbent polymer-coated and non-coated resilient coreparticles, nonresilient core particles or mixtures thereof.

DESCRIPTION OF THE REFERENCED NUMERALS

In reference to the drawings, similar reference characters denotesimilar elements throughout all the drawings. The following is a list,of the reference characters and associated element:

10 synthetic turf system

20 foundation

21 topside of foundation

30 backing layer

35 plurality of grass-like filaments

40 cooling mat

45 super absorbent polymer

50 infill

60 a first (bottom) infill layer

70 a second (top) infill layer

80 one or more third (middle) infill layers

90 one or more modified third (middle) infill layers

100 SAP-coated particles

110 superabsorbent polymer coating

120 core particle

130 binder

DETAILED DESCRIPTION

Before describing the present invention in detail, it is to beunderstood that this invention is not limited to particularlyexemplified systems or process parameters as such may, of course, vary.It is also to be understood that the terminology used herein is for thepurpose of describing particular embodiments of the invention only, andis not intended to limit the scope of the invention in any manner.

All publications, patents and patent applications cited herein, whethersupra or infra, are hereby incorporated by reference in their entiretyto the same extent as if each individual publication, patent or patentapplication was specifically and individually indicated as incorporatedby reference.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the content clearly dictates otherwise. Thus, for example,reference to a “colorant agent” includes two or more such agents.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the invention pertains. Although a number of methodsand materials similar or equivalent to those described herein can beused in the practice of the present invention, the preferred materialsand methods are described herein.

As will be appreciated by one having ordinary skill in the art, themethods and compositions of the invention substantially reduce oreliminate the disadvantages and drawbacks associated with prior artmethods and compositions.

It should be noted that, when employed in the present disclosure, theterms “comprises,” “comprising,” and other derivatives from the rootterm “comprise” are intended to be open-ended terms that specify thepresence of any stated features, elements, integers, steps, orcomponents, and are not intended, to preclude the presence or additionof one or more other features, elements, integers, steps, components, orgroups thereof.

Definitions

As used in the present specification, the following words and phrasesare generally intended to have the meanings as set forth below, exceptto the extent that the context in which they are used indicatesotherwise.

“Binder,” “binding agent” or “coupling agent” refers to a materialhaving binding, adhesive or attachment properties with or withoutchemical, thermal, pressure or other treatment. The term “binder”includes materials that are capable of attaching themselves to asubstrate or are capable of attaching other substances to a substrate.The binder component used in the coating compositions of this inventioncan include any polymeric material customarily used as a binder incoating compositions.

In one embodiment, the binder is a composition such as water,polyacrylate, lignin sulfonate (solid), polymeric binders, siliconepolymer, e.g., polyorganosiloxane, and combinations thereof. In anotherembodiment, the organic polymerizable binders include, but are notlimited to, carboxymethylcellulose (CMC) and its derivatives and itsmetal salts, guar gum cellulose, xanthan gum, starch, lignin, polyvinylalcohol, polyacrylic acid, styrene butadiene resins (SBR), andpolystyrene acrylic acid resins.

In one embodiment, the binders are selected from the group consisting ofacrylic acid grafted starch, alginates, alkoxysilanes, for example,tetraethoxy silane (TEOS), block co-polymers, carboxy methyl cellulose,carboxymethyl starch, carboxymethylcellulose, carrageenan gum, casein,celluloseacetate phthalate, cellulose based polymers,cellulosederivatives such as dextrans and starches, gelatin, guar gumcellulose, hydrolyzed acrylonitrile grafted starch, hydroxymethylcellulose, lignin, locust bean gum, maleic anhydride copolymers, methylcellulose, monomeric silanes, natural gums, pectins, poly(2-hydroxyethylacrylate), poly (ethyleneoxide), poly (sodiumacrylate-co-acrylic acid), poly(2-hydroxyethyl-methacrylate),poly(acrylamides), poly(acrylates), poly(ethers), poly(methacrylicacid), poly(N-vinyl pyrrolidone), polyvinyl alcohol), polyvinylsulfonates), poly(vinylsulfonic acid), polyesters, polyethylene oxide,polymeric binders, polymers formed from acid-group containing monomers,polyorganosiloxane, polystyrene acrylic acid resins, polyurethanes,polyvinylalcohol, polyvinylmethyl ether, polyvinylpyrrolidone,silicates, silicone polymer, starch, starch-based polymers, silanes,organosiloxanes, styrene butadiene resins, xanthan gum and mixturesthereof.

The term “coupling agent” refers to a binder that is used as an adhesionpromoter enhancing adhesion between a surface of an inorganic material,such as silica, and an organic material through chemical couplingtherebetween during formulation of the composition.

The term “cross-linking” or “cross-linked” used in reference to thesuperabsorbent polymer refers to any means for effectively renderingnormally water-soluble materials substantially water-insoluble butswellable. Such a cross-linking means can include for example, physicalentanglement, crystalline domains, covalent bonds, ionic complexes andassociations, hydrophilic associations such as hydrogen bonding,hydrophobic associations or Van der Wools forces. Superabsorbentpolymers include internal cross-linking and surface cross-linking.

“Performance-enhancing active” or “Performance-enhancing additive” asused herein, refers to any additive which is desirable to add to theinfill particles including an antimicrobial, an odor reducing material,a binder, a fragrance, a color altering agent, a dust reducing agent, anonstick release agent, a superabsorbent material, cyclodextrin,zeolite, activated carbon, a pH altering agent, a salt forming material,a ricinoleate, silica gel, UV stabilizers or protectants, crystallinesilica, activated alumina, an anti-clumping agent, and mixtures thereof.Performance-enhancing actives that inhibit the formation of odor includea water-soluble metal salt such as silver, copper, zinc, iron, andaluminum salts and mixtures thereof.

In one embodiment, the performance-enhancing additive is sprayed ontothe particles. In another embodiment, the performance-enhancingadditives are dry-blended with the particles. In another embodiment theperformance enhancing additive is blended with an elastomeric materialthan ground into particles.

The term “polymer” includes, but is not limited to, homopolymers,copolymers, for example, block, graft, random, and alternatingcopolymers, terpolymers, etc., and blends and modifications thereof.Furthermore, unless otherwise specifically limited., the term “polymer”shall include all possible configurational isomers of the material.These configurations include, but are not limited to isotactic,syndiotactic, and atactic symmetries.

“Polymer” as used herein, refers to a series of repeating monomericunits that have been cross-linked or polymerized. Any suitable polymercan be used to carry out the present invention. It is possible that thepolymers of the invention may also comprise two, three, four or moredifferent polymers. In some embodiments, of the invention only onepolymer is used. In some preferred embodiments a combination of twopolymers are used. Combinations of polymers can be in varying ratios, toprovide coatings with differing properties. Those of skill in the art ofpolymer chemistry will he familiar with the different properties ofpolymeric compounds. Examples of polymers that may be used in thepresent invention include, but are not limited to polycarboxylic acids,cellulosic polymers, proteins, polypeptides, polyvinylpyrrolidone,maleic anhydride polymers, polyamides, polyvinyl alcohols, polyethyleneoxides, glycosaminoglycans, polysaccharides, polyesters, polyurethanes,polystyrenes, copolymers, silicones, polyorthoesters, polyanhydrides,copolymers of vinyl monomers, polycarhonates, polyethylenes,polypropylenes, polylactic acids, polyglycolic acids, polycaprolactones,polyhydroxybutyrate valerates, polyacrylamides, polyethers, polyurethanedispersions, polyacrylates, acrylic latex dispersions, polyacrylic acid,mixtures and copolymers thereof. The polymers of the present inventionmay be natural or synthetic in origin, including gelatin, chitosan,dextrin, cyclodextrin, poly(urethanes), Poly(siloxanes) or silicones,Poly(acrylates) such as poly(methyl methacrylate), poly(butylmethacrylate), and Poly(2-hydroxy ethyl methacrylate), Poly(vinylalcohol) Poly(olefins) such as poly(ethylene), poly(isoprene),halogenated polymers such as Poly(tetrafluoroethylene)—and derivativesand copolymers such as those commonly sold as Teflon products,Poly(vinylidine fluoride), Poly(vinyl acetate), Poly(vinyl pyrrolidone),Poly(acrylic acid), Polyacrylamide, Poly(ethylene-co-vinyl acetate),Poly(ethylene glycol), Polypropylene glycol), Poly(methacrylic acid);etc.

The term “polyolefin” as used herein generally includes, but is notlimited to, materials such as polyethylene, polypropylene,polyisobutylene, and the like, the homopolymers, copolymers,terpolymers, etc., thereof, and blends and modifications thereof. Theterm “polyolefin” shall include all possible structures thereof, whichinclude, but are not limited to, isotatic, synodiotactic, and randomsymmetries. Copolymers include atactic and block copolymers.

The term “rubber” as used in relation to either rubber particles orrubber coated particles means any resilient elastomeric material,including natural and artificial rubbers, elastomers and polymers suchas thermoplastic polymers and elastomers and equivalent materials.

Examples of elastomers include acryl rubber, butyl rubber, carboxylatedacrylonitrile butadiene rubber (XNBR), carboxylated hydrogenatedacrylonitrile butadiene rubber (XHNBR), EPDM/acrylonitrile graftcopolymer, EPDM/styrene copolymer, epoxylated natural rubber, ethylenepropylene (EPR), ethylene-propylene copolymers, ethylene-propylene-dienemonomer (EPDM) rubber, ethylene-propylene-diene terpolymers,ethylenically unsaturated nitrile-conjugated diene-based high saturationcopolymer rubber, fluoroelastomers (FKM), halogenated butyl rubber,hereinafter called EPDM, hereinafter called EPM, hydrin rubber,hydrogenated acrylonitrile butadiene rubber (HNBR), hydrogenatedcarboxylated acrylonitrile butadiene rubber (HXNBR), maleated BIMScopolymer, maleated ethylene-acrylic acid copolymer, maleatedethylene-butene rubber, maleated ethylene-decene rubber, maleatedethylene-ethyl acrylate copolymer, maleated ethylene-hexene rubber,maleated ethylene-methyl acrylate copolymer, maleated ethylene-octenerubber, maleated ethylene-propylene copolymer rubber, maleatedethylene-vinyl acetate copolymer, maleated halogenatedisobutylene-isoprene copolymer, maleated isobutylene-isoprene copolymer,maleated isobutylene-paramethylstyrene copolymer, maleated star branchedbutyl (SBB) copolymer, maleic acid modified EPDM/acrylonitrile graftcopolymer, maleic acid modified EPDM/styrene copolymer, maleic anhydridegrafted acrylonitrile-butadiene-styrene rubber, maleic anhydride graftedethylene-propylene-diene rubber, maleic anhydride graftedstyrene-ethylene/butadiene-styrene rubber, natural rubbers, nitrileacrylonitrile butadiene rubber (NBR), nitrile butadiene rubber, nitrilerubber, perfluoroelastomers (FEKM), polyetheresters, polyethylene orpolypropylene homo- or copolymers and polyisobutylene, polyisoprene,polymers comprising a thermoplastic and an elastomer, polyurethanes,reactive phenoxy thermoplastic resins, styrene-butadiene rubber (SBR),styrene/maleic acid copolymer, tetrafluoroethylene and propylene monomer(FEPM) elastomers as well as copolymers and mixtures thereof.

Examples of thermoplastic elastomers (TPE) include:

-   -   1) Styrenic Block Copolymers (TPE-S) SBS is based on two-phase        blockcopolymers with hard and soft segments. The styrene end        blocks provide the thermoplastic properties and the Butadiene        mid-blocks provide the elastomeric properties. SBS when        hydrogenated becomes SEBS, as the elimination of the C═C bonds        in the butadiene component generated ethylene and butylenes        mid-block, hence the SEBS acronym. Much improved heat        resistance, mechanical properties and chemical resistance        characterize SEBS. Monprene® Tekron® and Elexar® products from        Teknor Apex are good examples of hydrogenated styrenic block        copolymers.    -   2) Thermoplastic Polyolefins (TPE-O or TPO) These materials are        blends of polypropylene (PP) and un-cross-linked rubber, in some        cases a low degree of cross-linking is present to boost heat        resistance and compression set properties.    -   3) Thermoplastic vulcanisates (TPE-V or TPV) These materials are        the next step up in performance from TPE-O. These are compounds        of PP and EPDM rubber, however they have been dynamically        vulcanized during the compounding step. The Uniprene® series        from Teknor Apex is a very good example of TPE-V. Uniprene XL        increases the upper temperature limit towards 140° C. with big        improvements in long terms compression set resistance versus        standard TPE-V materials. There are a number of new TPE-Vs being        introduced, termed “Super TPVs” which are based on engineering        plastics blended with high performance elastomers, which can        offer greatly improved heat and chemical resistance.    -   4) Thermoplastic polyurethanes (TPE-U or TPU) These materials        can be based on polyester or polyether urethane types and are        used in applications where a product requires excellent tear        strength, abrasion resistance, and flex fatigue resistance.    -   5) Thermoplastic copolyesters (TPE-E or COPE or TEEE) are used        where increased chemical resistance and heat resistance up to        140° C. are needed.    -   6) Melt processable rubber (MPR) is designed for more demanding        applications requiring chemical resistance, particularly        resistance to oil and grease, were MPR replaces cross-linked        nitrile rubber. It also possesses properties similar to those of        vulcanized rubber in noise-dampening applications and has        similar stress relaxation properties.    -   7) Thermoplastic polyether block amides (TPE-A) These products        offer the good heat resistance, have good chemical resistance        and bonding to polyamide engineering plastics.

In one embodiment, the synthetic rubber may be a butadiene rubbercomprising from about 100% to about 60% by weight of the composition. Inone embodiment, the butadiene rubber is polybutadiene orstyrene-butadiene rubber that preferably comprises from about 90% toabout 80% by weight of the composition. In one embodiment, however, thebutadiene rubber is a styrene-butadiene that comprises about 85-90% byweight of the composition. The synthetic rubber is preferably granulizedwith the granules having a diameter that allows for maximum sized airvoids while giving the desired degree of softness-hardness and strength.In one embodiment, the granule size ranges from about 1 millimeters toabout 10 millimeters in diameter. In one embodiment, the source for thegranulized synthetic rubber is recycled tires that are commerciallyavailable. In one embodiment, the granulized rubber is preferablycomprised of granulized reinforced polycord tires with no steel presentand with the polycord being comprised of nylon or polyester.

“Substrate” as used herein, refers to any surface upon which it isdesirable to deposit a coating comprising a polymer, a mix of polymersor water-absorbing materials. In the present invention, the substrate isgenerally made up of fine granules of stone, gravel, sand, asphalt,cement, ceramic beads, soil, clay, diatomaceous earth, perlite, silica,organic minerals, rubber or combinations thereof.

The term “superabsorbent materials” refers to water-swellable,water-insoluble organic or inorganic materials including superabsorbentpolymers and superabsorbent polymer compositions capable, under the mostfavorable conditions, of absorbing at least about 1 times their weight,or at least about 5 times their weight, or at least about 10 times theirweight in an aqueous solution. Superabsorbent materials include a“superabsorbent polymer” or “SAP”, a normally water-soluble polymerwhich has been cross-linked to render it substantially water insoluble,but capable of absorbing water. Numerous examples of superabsorbers andtheir methods of preparation may be found for example in U.S. Pat. Nos.4,102,340; 4,467,012; 4,950,264; 5,147,343; 5,328,935; 5,338,766;5,372,766; 5,849,816; 5,859,077; and U.S. Pat. Re. 32, 649.

SAPs generally fall into three classes, namely starch graft copolymers,cross-linked carboxymethylcellulose derivatives and modified hydrophilicpolyacrylates. Non-limiting examples of such absorbent polymers arehydrolyzed starch-acrylate graft co-polymer, saponified acrylic acidester-vinyl co-polymer, neutralized cross-linked polyacrylic acid,cross-linked polyacrylate salt., and carboxylated cellulose. Thepreferred. SAPs, upon absorbing fluids, form hydrogels. SAPs are wellknown and are commercially available from several sources.

The term “surface cross-linking” means that the level, of functionalcross-links in the vicinity of the surface of the superabsorbent polymerparticle generally is higher than the level of functional cross-links inthe interior of the superabsorbent polymer particle. As used herein,“surface” describes the outer-facing boundaries of the particle. Forporous superabsorbent polymer particles, exposed internal surfaces alsoare included in the definition of surface.

“Water-absorbing material” as used herein includes, but is not limitedto a hydrophilic polymer. “Water-absorbing material” as used hereinincludes, but is not limited to a highly absorbent material, which maycomprises a superabsorbent polymer. Examples of water-vapor trappingmaterials include, but are not limited to, acrylate polymers, generallyformed from acrylic acid, methacrylic acid, acrylate, methyl acrylate,ethyl acrylate, methyl methacrylate, ethyl methacrylate, adialkylaminoalkyl acrylate, a dialkylaminoalkyl methacrylate, atrialkylammonioalkyl acrylate, and/or a trialkylammonioalkylmethacrylate, and include the polymers or copolymers of acrylic acid,methacrylic acid, methyl methacrylate, ethyl methacrylate,2-dimethylaminoethyl methacrylate, and trimethylammonioethylmethacrylate chloride. Examples of hydrophilic polymers include, but isnot limited to poly(N-vinyl lactams), poly(N-vinyl acrylamides),poly(N-alkylacrylamides), substituted and unsubstituted acrylic andmethacrylic acid polymers, polyvinyl alcohol (PVA), polyvinylamine,copolymers thereof and copolymers with other types of hydrophilicmonomers (e.g. vinyl acetate), polysaccharides, cross-linked acrylatepolymers and copolymers, carbomers, cross-linked acrylamide-sodiumacrylate copolymers, gelatin, vegetable polysaccharides, such asalginates, pectins, carrageenans, or xanthan, starch and starchderivatives, galactomannan and galactomannan derivatives, polyvinylpyrrolidone (PVP), poly(N-vinyl caprolactam) (PVCap), poly(N-vinylacetamides), polyacrylic acid, polymethacrylic acid, and copolymers andblends thereof. PVP and PVCap. Examples of superabsorbent polymersinclude hydrogels. Copolymers of any of the water-vapor trappingmaterials mentioned herein, and blends thereof may also be used.

The term “% by weight” or “% wt” when used herein and referring tocomponents of the superabsorbent polymer composition, is to beinterpreted as based on the weight of the dry superabsorbent polymercomposition, unless otherwise specified herein.

These terms may be defined with additional language in the remainingportions of the specification.

1. Description of the Cooling Layer

FIG. 1 is an illustration of an exemplary embodiment of a synthetic turfsystem 10 of the present invention. As shown, the synthetic turf systemcomprises a backing layer 30 resting upon a foundation 20.

The foundation may be bare ground, gravel, sand, rubber, constructionmaterials, or a combination thereof with stone or other similarmaterials in order to provide support and adequate drainage for thesynthetic turf system.

The foundation may be slightly angled towards strategically placed drainpipes to better and faster drying of the synthetic turf systems topsurface after rain or melted snow.

The backing layer may be comprised of any known woven, non-woven, orspun-bonded fabric to which grass-like filaments 35 may be attached.Examples of conventional backing layers include woven warp type strandsor slit film and cross or woof type strands or slit film to produce awoven sheet. It is preferred that the backing layer comprise of astable, weather resistant material such as polyolefins, nylon, orsimilar material.

The backing layer is preferably supple and flexible such that it mayconform to the foundation layer and potentially give when impacted. Thebacking layer may also include one or more openings for movement offluids such as, for example, water.

Grass-like filaments 35 are attached to the backing layer such that thegrass-like filaments extend substantially upward, away from thefoundation and backing layer. The grass-like filaments may be groups offilaments individually attached to the backing layer or thickindividual, filaments that are split at the top to give the appearanceof numerous individual fibers.

The grass-like filaments may vary in thickness and size to give anappearance of natural grass. Typically, the grass-like filaments arecomprised of one or more polyolefins, one or more nylons, or the like.

Any known foundation, backing layer and grass-like filaments may he usedin the various exemplary embodiments of the present invention.

The synthetic turf system may be further comprised of a cooling mat 40positioned between the topside of the foundation and the backing layer.The cooling mat may be comprised of one or more layers. When more thanone layer comprises the cooling mat, each layer of the cooling mat mayhe of different compositions than other layers. At least one of thelayers is comprised of super absorbent polymers on a fibrous substrate.

In exemplary embodiments, the cooling mat may be positioned between thetopside of the foundation and the backing layer, as illustrated inFIG. 1. In other exemplary embodiments, as illustrated in FIG. 2, thecooling mat may be positioned above the backing layer. In suchembodiment, it is preferred that the grass-like filaments are tuftedthrough the cooling mat and primarily attached to the backing layer. Ina similar variation, the super absorbent polymer may be formed such thatit is cross-linked and polymerized to a tube-shaped surround throughwhich the grass-like filaments are substantially enclosed and attachedto the backing layer.

In yet another exemplary embodiment, the cooling mat may be positionedboth between the foundation and the backing layer, and above the backinglayer, such that there are multiple cooling mat layers. In yet anotherexemplary embodiment, the cooling mat may be positioned between a firstbacking layer and a second backing layer.

In other exemplary embodiments, the plurality of grass-like filamentsare tufted or attached directly to the cooling mat, and there is not anadjacent or attached backing layer. This embodiment is illustrated, forexample, in FIG. 3.

The fibrous substrates of the cooling mat may be woven or non-woven,including woven or non-woven polyester, woven or non-woven fiberglass,needle-punched polyester or polyolefin, or any other fibrous substratethat can be coated. Examples of fibrous substrates include spun-bondedpolyester or polyolefin. Fibrous substrates useful in the presentinvention may also be made of other polymers such as, for example, nylonand Kevlar; natural fibers such as, for example, flax, hemp, and wool;or combinations thereof.

The super absorbent polymers of the cooling mat may be, for example,polymers or copolymers of partially neutralized acrylic acid,acrylamide, or acrylic esters as copolymer only. Preferably, the superabsorbent polymer may swell in water or other introduced liquids up toabout 200 to about 400 times its size. It is also preferred that thesuper absorbent polymers are nontoxic.

The cooling mat may be prepared by dipping, spraying, and/or dotspraying an aqueous solution of an acrylic monomer and cross-linkingagent onto the fibrous substrate. Upon polymerization of the acrylicmonomer, the resultant cross-linked polymer should be substantiallyentangled within the fibrous substrate.

In an exemplary embodiment, the acrylic monomer solution is in the formof the partially neutralized acrylic acid. The partially neutralizedacrylic acid is introduced in water to one or more cross-linking agentsand UV-sensitive or peroxide reagents. A UV-light or heat may be used toform the polymer as a cross-linked polymer without the cross-linkingmonomers, but the cross-linking agents assist in better controlling thelevel and degree of cross-linking and strength associated withcross-linked polymers.

Polymerization of the one or more super absorbent polymers may occur viaexposure to ultraviolet (UV) light radiation, peroxides, or other knownpolymerization process. UV-dependent photoinitiators of polymerizationuseful in exemplary embodiments of the present invention arewater-soluble or water dispersible compounds that generate free radicalsupon exposure to UV irradiation. Examples of such polymerizationinitiators include,4-benzoyl-N,N-dimethyl-N-(2-(1-oxo-2-propenyloxy)ethyl)benzenemethananaminiumbromide (available commercially as Quantacure ABQ) in combination withN-methyl-diethanolamine (NMDEA), and2-hydroxy-2-methyl-1-phenyl-1-propanone (available commercially asDarocure 1173).

When the super absorbent polymers are contacted with water, the superabsorbent polymers increase dramatically in size. Depending on therelative size and thickness, the super absorbent polymers may reachmaximum moisture retention in as quickly as about ten minutes can reachmaximum hydration in as little as ten minutes or as much as days. Afterreaching maximum moisture retention the retained moisture slowlyreleases from the super absorbent polymers depending on the particularconditions present, such as, for example, ambient temperature, sunlight,humidity, etc. Typically, the moisture evaporates from the superabsorbent polymers and thereby keeps the backing layer and grass-likefilaments cool.

Polymerization and cross-linking of the acrylic monomers andcross-linking agents to form super absorbent polymers within the coolinglayer significantly ensures limited movement of the resultant superabsorbent polymers relative to the cooling layer, thereby substantiallymaintaining within the associated synthetic turf system despite weather,traffic, water flow, and the like upon the synthetic turf system.Maintaining the super absorbent polymers within the synthetic turfsystem decreases the need to have to reintroduce or resupply thesynthetic turf system with cooling materials.

Cross-linking agents instrumental in propagating the polymerization andforming a branched network of polymers include, for example,N,N-methylene bis acrylamide (NMBA), polyethylene glycol diacrylate(PEGDA) and polyethylene glycol dimethacrylate (PEGDMA).

A solution of a polymer, that is, for example, a non-cross-linkedacrylic polymer, and a cross-linking agent may also be injected into oneor more layers of an already-installed traditional synthetic turfsystem, such that the acrylic polymers are injected into and/or onto thesynthetic turf immediately upon being admixed. The means of injectingsubstances such as, for example, acrylic polymer solutions andcross-linking reagents is known in the art.

The various exemplary embodiments of the present invention furtherinclude a method of cooling a synthetic turf system, that is, forexample, a traditional synthetic turf system that has already beeninstalled. The synthetic turf system may be comprised of a foundation,wherein the foundation is selected from one or more of bare ground,stone, gravel, sand, asphalt, cement, rubber, and constructionmaterials; and a plurality of grass-like filaments attached to a backinglayer such that the backing layer is substantially adjacent to thetopside of the foundation and the plurality of grass-like filamentsextend substantially upward from the backing layer. The method includesthe steps of introducing a solution of one or more non-cross-linkedacrylic polymers and one or more cross-linking agents into or below thesynthetic turf system; and cross-linking the acrylic polymer to form oneor more superabsorbent polymers. The solution may be introduced viaspraying or injecting, and then cross-linked once it is introduced tothe desired location relative to the synthetic turf system.

In addition to introducing super absorbent polymers into one or morelayers of a traditional synthetic turf, a solution of one or morenon-cross-linked acrylic polymers and one or more cross-linking agentsmay be injected or introduced into a synthetic turf in this mannerhaving a cooling mat as set forth herein, in order to resupply,energize, and/or otherwise increase the water retention and coolingeffect of the cooling mat.

The life of the super absorbent polymers depends on various conditions,including, for example, adjacent soil conditions, microbes that feed onthe super absorbent polymers, fungi, UV, foot traffic, weatherconditions, and the like. Some super absorbent polymers may have a lifeof several years and have an estimated cost of less than about one thirdof a comparative amount of rubber granules.

The cooling mat may be further comprised of at least one neutralizingmaterial to assist in controlling moisture content and liquid absorbingcapacities of the super absorbent polymers.

In various exemplary embodiments, the cooling mat is bonded to thebacking layer. The bonding may be by way of one or more adhesives, forexample. The cooling mat may also be attached to the backing layer via amechanical means of stitching and/or stapling, for example, by way ofthe attached grass-like filaments and/or other thread. In other variousexemplary embodiments, the cooling mat and backing layer are adjacentbut not chemically or mechanically attached.

In a preferred embodiment, even when the super absorbent polymers swellor expand to the greatest extend with water or other fluid, the coolingmat still has channels or openings allowing water, air, moisture, or acombination thereof to flow through to the foundation and ground orevaporation through the synthetic turf system. Such channels or openingsdecrease pooling of water or fluids on the surface of the synthetic turfsystems as well.

The cooling mat of exemplary embodiments herein is preferably of an openstructure to allow some flow of liquids, air, moisture, or a combinationthereof through the cooling layer.

Moisture evaporation will absorb much of the heat from the syntheticturf system. The cooling mat substantially holds moisture in the polymerand slowly allows evaporation, substantially controlled by diffusion ofmoisture out of the polymer, cooling the synthetic turf system overtime.

The synthetic turf according to the various exemplary embodiments hereinmay further include a particulate infill comprised of one or more superabsorbent polymers, sand, rubber granules, ceramic beads, soil andcombinations thereof. Such particulate infill may be positioned betweenand around the grass-like filaments.

In various exemplary embodiments of the present invention, whencombining super absorbent polymers with sand, rubber granules, ceramicbeads, soil or combinations thereof, the particulate infill issubstantially homogeneous. That is, for example, it is preferred invarious exemplary embodiments that the particulate infill not be dividedinto various layers of materials.

The particulate infill materials, in conjunction with the grass-likefilaments attached to the backing layer, tend to mutually stabilize andhold one another in predetermined position. However, as the superabsorbent polymers change size depending on moisture conditions, thereis some shifting of the particulate infill materials.

When the super absorbent polymers are at a higher moisture retention,the super absorbent polymers are more flexible and absorb impartedimpacts more effectively, thereby potentially reducing injuries toindividuals hitting the synthetic turf system. The overall desiredflexibility of impact absorption and playing characteristics desired bya synthetic turf system may be manipulated by varying the percentage ofsuper absorbent polymers in the particulate infill.

Natural grass may be grown within and through the synthetic turf system.The natural grass may provide a more realistic appearance to thesynthetic turf system. The synthetic turf system may further comprisenutrients for natural grass. In another embodiment, the synthetic turfsystem may further comprise controlled release nutrients.

The synthetic turf system may further comprise an underground sprinklersystem for applying water to the super absorbent polymers as needed, oneor more thermal probes for determining the temperature of the synthetictuft systems, or a combination thereof. The one or more thermal probesmay be a thermocouple system in substantial contact with the syntheticturf system and would allow remote monitoring of the installation.

The super absorbent polymers and/or the cooling mat may further betreated with one or more antimicrobial agents, one or more anti-freezingagents, or a combination thereof.

2. Description of the SAP-Coated Substrates

As described herein, it is desirable to have a superabsorbent polymer(SAP) in the infill of synthetic turf to provide a source of water forevaporative cooling of the turf surface during hot weather. Hydrated SAPis a soft material that can change the athletic performance propertiesof the turf if it is concentrated within the turf infill.

It has now been found that in order to prevent undesirable changes inthe turf caused by concentrated areas of SAP, it is advantageous to havethe SAP widely distributed within the turf infill material(s). Widedistribution allows enough SAP to be present in the infill to provideevaporative cooling, but the amount of SAP in any discrete area is notenough to change the turf performance properties.

FIG. 4 is an illustration of an exemplary embodiment of a synthetic turfinfill cooling particles 100 of the present invention. As shown, thecooling particle 100 comprises a layer of water-absorbing material nocoating a foundation comprising a core substrate 120. In one embodiment,the cooling particle 100 is comprised of a core particle or substrate120, which is coated with a water-absorbing material. In one embodiment,the water-absorbing material is a super absorbent polymer.

According to another embodiment, as illustrated in FIG. 5, comprising acore 120, a binder 130 surrounding the core 120 in the form of acoating, layer or shell and water-absorbing material no surrounding thebinder-coated core 120 to form the final water-absorbing particle. Inanother embodiment, the water-absorbing material “surrounds” a core orsubstrate (e.g., sand, ground rubber, powder, granules, clumps, etc.)forming a water-absorbing particle 100.

In one embodiment, a coupling agent or binder 130 is used between thesubstrate 120 (e.g., rubber particles, silica sand grains, etc.) and thewater-absorbing material coating material 110. Such binders arecharacterized by having an improved adherence to the surface of the coreas well as to the water absorbing coating material as compared to theadherence between the coating material and the core surface when beingin direct contact. The hinders may be used alone or in a combination oftwo or more thereof.

In one embodiment, the binding agent is a silane. In another embodiment,the silane is one or more organosilozane, silane monomer, or mixturesthereof.

In one embodiment, the binding agent is bifunctional slime comprising areactive amino group and a hydrolyzable inorganic triethoxysilyl group,so that the silane binds to inorganic materials, i.e. the sand grainsand rubber particles, as well as to organic polymers, i.e. the coatingmaterial. In one embodiment, the bifunctional slime is3-aminopropyltriethoxysilane (H₂N—(CH₂)₃—Si(OC₂H₅)₃), which is sold bythe company Degussa under the trade name of Dynasylan Ameo. The silaneis typically applied in a thin layer on the surface of the core in anamount of about 0.05 to about 0.5% by weight of the core, and morepreferably in an amount of about 0.1. to about 0.3% by weight.Combinations of the mentioned coupling agents with each other or withother coupling agents may alternatively be applied.

In one embodiment, the binding agent is selected from the groupconsisting of 3-glycidoxypropyl)trimethoxysilane,(cyclohexyl)methyldimethoxysilane, 3-(triethoxysily)propylsuccinicanhydride, dicyclopentylidimethoxysilane, dimethyldiethoxysilane,dimethyldimethoxysilane, isooctyltriethoxysilane,isooctyltrimethoxysikme, methyltriethoxysilane, methyltrimethoxysilane,N-(2-aminoethyl) (3-aminopropyl)methyldimethoxysilane,N-(2-aminoethyl)(3-aminopropyl)triethoxysilane,N-(2-aminoethyl)(3-aminopropyl)trimethoxysilane,N-(3-(triethoxysilyl)propyl)methylurethane,N-(3-(triethoxysilyl)propyl)urea,N-cyclohexylaminomethylmethyldiethoxysilane, phenyltriethoxysilane,tetraethoxysilane, and tetramethoxysilane.

A binder may be added to the mixer prior to the superabsorbant polymer,which provides a layer of the binder on the surface of the coreparticles before the superabsorbant polymer is added to the content ofthe mixer, thereby improving the binding between the core and thesuperabsorbant polymer. In another embodiment, the binder may be addedto the mixer simultaneously with the superabsorbant polymer, whichprovides improved physical integrity of the superabsorbant polymer.

In some embodiments of the invention, the average thickness of thecoating is from about 1 to about 1000 μm. In another embodiment, theaverage thickness of the coating is from about 5 μm to about. 500 μm. Inanother embodiment, the average thickness of the coating is from about10 μm to about 250 μm. In another embodiment, the average thickness ofthe coating is from about 10 μm to about 100 μm.

A particle 100 of water-absorbing material coated granular material isshown diagrammatically in FIGS. 4 and 5. Particle 100 includes a core120 of granular material, which may be fabricated of a metallicmaterial, a ceramic material, a stone material, a mineral material, ahard plastic material or any other hard material. In another embodiment,the core 120 comprises a granular material. In one embodiment, the core120 is a particle of sand, and in another embodiment, quartz sand. Inanother embodiment, the core 120 comprises a resilient particle. Inanother embodiment, the core 1.20 comprises a polymer material. Inanother embodiment, the core 120 comprises a rubber material. In anotherembodiment, the core 120 comprises SBR crumb rubber.

The resilient, particles and the particles 100 of water-absorbingmaterial coated granular material have a median size that is within arange of about 5 to about 60 mesh. More preferably, both types ofparticles have a median size that is substantially within a range ofabout 10 to about 45 mesh.

in another embodiment, the particles 100 of water-absorbing materialcoated granular material are fabricated so that the water-absorbingmaterial coating comprises about 0.2% to about 10% by weight of core 120of granular material. In another embodiment, the water-absorbingmaterial coating comprises about 0.4% to about 5.0% by weight of thecore 120 of granular material. In another embodiment, thewater-absorbing material coating comprises about 0.6% to about 3.0% byweight of the core 120 of granular material.

The core 120 of granular material is preferably quartz sand and ispreferably of an overall grain diameter in the range of about (mominches to about 0.2 inches, and in another embodiment, in the range ofabout 0.001 inches to about 0.1 inches, and most preferably in the rangeof about 0.015 inches to about 0.05 inches.

In some embodiments of the invention, a lightweight or heavyweight corematerial can be used to import differing performance characteristics.The core can be solid, hollow, absorbent, nonabsorbent, and combinationsof these. In some embodiments of the invention, lightweight corematerials include but are not limited to calcium bentonite clay,attapulgite clay, perlite, silica, non-absorbent silicious materials,sand, plant seeds, polymeric materials, ground rubber and mixturesthereof. In some embodiments of the invention, heavyweight cores may beused when it is desirable to have heavier particles. Heavy particles maybe useful, for example, to add ballast to the field. Illustrativeheavyweight core materials include but are not limited to sand, stone,metal, glass, clay, etc.

In one embodiment, water-absorbing materials may be used as the core ofthe particle without departing from the spirit and scope of the presentinvention. Illustrative absorbent materials include but are not limitedto minerals, fly ash, absorbing pelletized materials, perlite, silicas,other absorbent materials and mixtures thereof. In one embodiment,minerals include: bentonites, zeolites, fullers earth, attapulgite,montmorillonite diatomaceous earth, opaline silica, crystalline silica,silica gel, alumina, Georgia White clay, sepiolite, calcite, dolomite,slate, pumice, tobermite, marls, attapulgite, kaolinite, halloysite,smectite, vermiculite, hectorite, Fuller's earth, fossilized plantmaterials, expanded perlites, gypsum and other similar minerals andmixtures thereof.

A suitable superabsorbent polymer may be selected, from natural,biodegradable, synthetic and modified natural polymers and materials.Superabsorbent polymers include internal cross-linking. Thesuperabsorbent polymer composition may include surface treatment of thesuperabsorbent polymer as set forth herein.

In one embodiment, the superabsorbent polymer of the present inventionis obtained by the initial preparation of a polymeric resin by thepolymerization of from about 55 to about 99.9 wt. % of polymerizableunsaturated acid group containing monomers. Suitable monomers includethose containing carboxyl groups, such as acrylic acid, methacrylic acidor 2-acrylamido-2-methylpr-opanesulfonic acid, or mixtures of thesemonomers are preferred here. In one embodiment, at least about 50-weight%, and more preferably at least about 75 wt. % of the acid groups to becarboxyl groups.

In one embodiment, monomers, which can be used for the preparation ofthe polymeric resins according to the present invention, are 0-40 wt. %of ethylenically unsaturated monomers which can be copolymerized withacrylamide, methacrylamide, hydroxyethyl acrylate,dimethylaminoalkyl(meth)-acrylate, ethoxylated(meth)-acrylates,dimethylamiopropylacrylam-ide or acrylamidopropyltrimethylammoniumchloride. More than 40 wt. % of these monomers can impair theswellability of the polymers.

In another embodiment, the superabsorbent polymers of the presentinvention may be surface cross-linked after polymerization. Surfacecross-linking is any process that increases the cross-link density ofthe polymer matrix in the vicinity of the superabsorbent particlesurface with respect to the cross-linking density of the particleinterior. The superabsorbent polymers are typically surface cross-linkedby the addition of a surface cross-linking agent. Preferred surfacecross-linking agents include chemicals with one or more functionalgroups, which are reactive towards pendant groups of the polymer chains,typically the acid groups. The content of the surface cross-linkingagents is from about 0.01 to about 5 wt. %, and preferably from about0.1 to about 3.0 wt. %, based on the weight of the dry polymer.

In one embodiment, the SAP polymer is in solution as an uncross-linkedlinear polymer as it is coated onto the infill particles, which is thencross-linked after the substrate/core particle is coated.

In one embodiment, the SAP is manufactured using a cross-linked aqueoussolution polymer composition consisting of about 15 wt-% to about 50wt-% of at least one water-soluble monomer and a cross-linking agent asdescribed in U.S. Pat. No. 7,438,951 by Anderson et al. and assigned toH. B. Fuller Licensing & Financing, Inc., incorporated herein in itsentirety for all purposes.

In one embodiment, the at least one water-soluble monomer is an alpha,beta-ethylenically unsaturated carboxylic acid monomer. In oneembodiment, the polymer solution is sufficiently low enough in viscositysuch that it can be applied in aqueous form, yet after cross-linkingpossesses a fast rate of acquisition and is highly absorbent.

In one embodiment, the aqueous polymer composition consists essentiallyof one or more water-soluble monomers, preferably at least one alpha,beta-ethylenically unsaturated carboxylic acid monomer and across-linking agent. In another embodiment, the polymer is produced froma solution polymerization of the monomer(s) that is subsequentlyneutralized with a base to a pH ranging from about 7 to 10. In anotherembodiment, the extent of cross-linking and compatibility of thecross-linking agent is controlled by employing a portion of volatilebase in the neutralization process. In another embodiment, thedissipation of the base upon application liberates a controlledconcentration of carboxylic groups to allow cross-linking. In anotherembodiment, prior to cross-linking, the polyacrylate composition has aviscosity ranging from about 50 cPs to about 20,000 cPs and preferablyfrom about 100 cPs to about 5,000 cPs for about a 20 wt-% solids contentsolution. In another embodiment, the cross-linking agent is added at aweight ratio of 10 parts polyacrylate polymer to 1 part cross-linkingagent. In another embodiment, the aqueous superabsorbent polymercomposition is combined with various water-based adhesives to improvethe flexibility, and/or hydrophilic properties and/or adhesiveproperties and/or cohesive strength. In another embodiment, thewater-based adhesives are selected and employed at concentrations suchthat the absorbent nature of the SAP polymer is not adversely impaired.

In one embodiment, the superabsorbent polymer composition of the presentinvention comprises an aqueous medium of 5 wt-% to about 65 wt-% solidsof a polymer prepared by an aqueous solution polymerization of one ormore water-soluble monomers. The preferred water-soluble monomers arealpha, beta-ethylenically unsaturated mono- or dicarboxylic acids andacid anhydrides, such as acrylic acid, methacrylic acid, crotonic acid,maleic acid/anhydride, itaconic acid, fumaric acid and the like withacrylic acid being the most preferred. The polymerization of suchmonomers produces an alkali soluble polyelectrolyte. Small amounts ofother water-soluble monomers may be incorporated. Examples may include2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, vinyl pyrolidone,acrylamide, methacrylamide, sodium vinyl sulfonate,1-allyloxy-2-hydroxypropane sulfonate, etc. The invention alsocontemplates the use of small amounts of water insoluble monomersprovided the intended properties of the pre-cross-linked and/orpost-cross-linked polymer are not adversely affected.

Any free radical generating source, such as peroxides and persulfates,may be used to initiate the polymerization of the monomers and carry outthe polymerization well known to those skilled in the art. Further,chain transfer agents known in the art may be employed to alter themolecular weight.

In one embodiment, the aqueous composition of the carboxylicacid-containing polymer contains about 5 wt-% to about 65 wt-%,preferably about 10 wt-% to about 50 wt-%, and more preferably about 20wt-% to about 40 wt-% solids. Once polymerized, the aqueous compositionis adjusted to a pH of about 7-10 using an alkali metal hydroxide, suchas sodium hydroxide or potassium hydroxide, and/or an alkaline earthmetal hydroxide, such as calcium hydroxide. Further, a metal alkoxidecan be used in place of the metal hydroxide. It is preferred to firstneutralize from about 50% to 95%, more preferably from about 65% to 85%and most preferably about 75% of the acid groups with the alkali metalhydroxide and then further neutralized with a volatile fugitive alkalinecomponent to a pH of 7.0 or above. At least a portion of thevolatile/fugitive base dissipates upon application of the aqueous SAP tothe substrates, but not prior to use. The dissipation of the baseliberates a sufficient portion of the carboxylate groups to the freeacid (carboxylic) form. This liberation allows for reaction with thecross-linking agent.

In another embodiment, the viscosity of the polymer solution ranges fromabout 50 cPs to about 50,000 cPs, more typically from about 100 cPs toabout 30,000 cPs, preferably from about 100 cPs to about 20,000 cPs,more preferably from about 100 cPs to about 10,000 cPs, even morepreferably from about 100 cPs to about 5,000 cPs and most preferablyfrom about 100 cPs to about 2500 cPs. At too high of a viscosity theaqueous solution is difficult to handle and process, whereas at too lowof a viscosity the ability to absorb fluid is substantially diminished.In one embodiment, the aqueous polyacrylate polymer is sufficiently lowin viscosity such that the composition may be applied via spraytechniques and/or saturate and/or coat a surface or substrate.

In another embodiment, a sufficient amount of cross-linking agent isadded to the aqueous polymer composition. Suitable cross-linking agentsinclude any substance that will react with the hydrophilic groups of theaqueous solution polymer. In one embodiment, the selection andconcentration of cross-linking agent will affect the absorbent rate andcapacity. It is desirable that the cross-linking agent employed “reacts”with the functional groups on the polyacrylate polymer in less than 24hours and at ambient (20° C.) and/or elevated temperatures.

In another embodiment, the objects of the present invention are attainedin a dry, solid, water-swellable, water-insoluble absorbent compositionof matter comprising an ionic complex of a water-soluble anionicpolyelectrolyte and a polyvalent metal cation having a valence of atleast 3, the cation being present in the amount of 0.01-5.0milliequivalents per gram of poly-electrolyte as described in U.S. Pat.No. 4,090,013 to Ganslaw et al., and assigned to National Starch andChemical Corp., incorporated herein in its entirety for all purposes. Inanother embodiment, the composition provides a gelatinous agglomerate ofliquid-swollen particulate members in the presence of a quantity of bodyexudate, is capable of absorbing at least about fifteen times its weightin body exudate, is capable of retaining absorbed exudate when exposedto pressure sufficient to deform the agglomerate, and is capable ofuncomplexing at an elevated pH and recomplexing at a lower pH. Thelatter feature enables its application to a substrate by conventionalfluid application techniques.

In another embodiment, the poly-electrolyte generally contains anionicgroups, such as carboxylate, sulfonate, sulfate and phosphate groups,and mixtures thereof. In another embodiment, the up to 95%, andpreferably 40-85%, of such groups may be neutralized to enhanceabsorbency of the composition. In another embodiment, thepoly-electrolyte is a synthetic polymer. In another embodiment, thepoly-electrolyte is polyacrylic acid.

In another embodiment, the cation is a metal, preferably aluminum, iron,chromium, zirconium, titanium, or mixtures thereof, with aluminum beingespecially preferred. In another embodiment, the cation is optimallypresent in the amount of 0.1-1.0 milliequivalents per gram ofpoly-electrolyte. In another embodiment, the poly-electrolyte ispolyacrylic acid having 40-85% of its carboxylate groups neutralized,and the cation is aluminum and is present in the amount of 0.1-1.0milliequivalents per gram of poly-electrolyte.

In another embodiment, the poly-electrolyte is poly-electrolyte is anatural or synthetic polymer characterized by substantialwater-solubility in an aqueous medium of some relatively neutral pH(somewhere from 2.0 to 8.5 pH) and by the presence of anionic groups(preferably carboxyl, sulfonate, sulfate or phosphate anionic groups).In another embodiment, the natural polymers are the anionic derivativesof starch or cellulose, and the preferred synthetic polymers are thecarboxylic acid homopolymers or copolymers containing at least 20 molepercent carboxylic acid units, e.g., polyacrylic acid.

In another embodiment, the poly-electrolyte is carboxylicacid-containing poly-electrolytes are the synthetic copolymers ofethylenically unsaturated monomers with mono-ethylenically unsaturatedcarboxylic acids or partially neutralized salts thereof. Examples of thepreferred α,β-mono-unsaturated carboxylic acids include acrylic acid,methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconicanhydride, fumaric acid., half esters or half amides of maleic, fumaricand itaconic acid, crotonic acid, etc. Examples of the preferredα,β-ethylenically unsaturated monomers include acrylamide ormethacrylamide and their N and N,N dialkyl derivatives containing 1-18carbon alkyl groups, alkyl acrylates and methacrylates containing 1-18carbon alkyl groups, vinyl esters, vinyl aromatic compounds, dienes,etc.

In another embodiment, the homopolymers of monoethylenically unsaturatedcarboxylic acids or mixtures of these monomers may also be used.Examples include acrylic and methacrylic acid homopolymers and acrylicacid/methacrylic acid copolymers.

In another embodiment, the sulfonic acid-containing polyelectrolytes arethe homopolymers of monoethylenically unsaturated sulfonic acids (orsalts thereof) and copolymers thereof with the aforementionedethylenically unsaturated monomers. Suitable sulfonate-containingmonomers include aromatic sulfonic acids (such as styrene sulfonicacids, 2-vinyl-3-bromobenzenesulfonic acid,2-vinyl-4-ethylbenzenesulfonic acid, 2-allylbenzene sulfonic acid,vinylphenylmethane-sulfonic acid and 1-sulfo-3-vinylphenylmethanesulfonic acid), heterocyclic sulfonic acids (such as2-sulfo-4-vinylfurane and 2-sulfo-5-allylfurane), aliphatic sulfonicacids (such as ethylenesulfonic acid and 1-phenylethylene sulfonicacid), sulfonic acids containing more than a single acid radical (suchas α-sulfoacrylic acid and α-sulfoethylenesulfonic acid), and sulfonicacid derivatives hydrolizable to the acid form (such as alkenyl sulfonicacid compounds and sulfoalkylacrylate compounds).

In another embodiment, the sulfate-containing polyelectrolytes are thoseformed by reacting homopolymers and copolymers containing hydroxylgroups or residual polymer unsaturation with sulfur trioxide or sulfuricacid; for example, sulfated polyvinyl alcohol, sulfated hydroxyethylacrylate, sulfated hydroxypropyl methacrylate. Exemplary of thephosphate-containing poly-electrolytes are the homopolymers andcopolymers of ethylenically unsaturated monomers containing a phosphoricacid moiety, such as methacryloxy ethyl phosphate.

In another embodiment, the poly-electrolytes formed of natural polymersand their derivatives are the carboxylated, sulfonated, sulfated, andphosphated derivatives of cellulose and starch, such as carboxymethylcellulose and carboxymethyl starch. Naturally occurring anionicpoly-electrolytes such as alginates, carrageenen, proteins (such asgelatin, casein, and soya protein), gum arabic, algin, agar, gum ghattialso have utility.

In another embodiment, the polyvalent metal cation complexes the abovedescribed poly-electrolyte to render the overall polymer compositesubstantially insoluble yet highly swellable. The cations have a valenceof at least three and are cations of metals belonging to the followinggroups of the periodic table: IIIB, IVB, VB, VIB, VIIB, VIII, IIIA, IVA,VA, VIA. The preferred metals are aluminum, zirconium, chromium,titanium and iron, and to a lesser degree antimony and bismuth. Aluminumis an especially preferred metal.

In another embodiment, the metal compound can be added prior to, duringpolymerization or post-added to a polymeric poly-electrolyte solution,the only restraint being that the metal compound be at least ionizableor soluble in the polymer system. The polyvalent metal can be added tothe composition by means of a basic, acidic or neutral salt, hydroxide,oxide or other compound or complex which has at least limited solubilityin water or an organic solvent in which the poly-electrolyte and/or itsconstituent monomers are also soluble at the time of cation introduction

In another embodiment, the inorganic salts include chlorides, nitrates,sulfates, borates, bromides, iodines, fluorides, nitrites, perchlorates,phosphates, and sulfides, such as aluminum chloride, aluminum sulfate,ferric sulfate, ferric nitrate, antimony trichloride, bismuth chloride,zirconium chloride, chromic sulfate, and chromic nitrate. Examples oforganic salts include salts of carboxylic acids such as carbonates,formates, acetates, butyrates, hexanoates, adipates, citrates, lactates,oxalates, oleates, propionates, salicylates, glycinates, glycollates andtartrates; for example, aluminum formoacetate, basic aluminum acetate,chromic acetate, aluminum citrate, aluminum diformate, aluminumtriformate, titanium oxalate, ferric acetate, aluminum octate, ferricoleate, zirconium lactate and zirconium acetate.

In another embodiment, the ammonia and amine complexes (and especiallythose coordinated with ammonia) of these metals are particularly useful.Amines capable of complexing include morpholine, monoethanol amine,diethylaminoethanol and ethylenediamine. Examples of these aminecomplexes include ammonium zirconyl carbonate, ammonium zirconylglycinate, and ammonium zirconium chelate of nitrilotriacetic acid.Polyvalent metal complexes (salts) of organic acids that are capable ofsolubilization in an alkaline pH range may also be employed. Such anionsas acetate, glutamate, formate, carbonate, salicylate, glycollate,octoate, benzoate, gluconate, oxalate and lactate are satisfactory.Polyvalent metal chelates wherein the ligand is a bidentate amino acid,such as glycine or alanine, are particularly useful.

Other organic compounds containing polyvalent metals are also useful;for example, the metal alkoxides, metal alkyls, and acetyl acetonates,such as aluminum isopropoxide, titanium acetyl acetonate, aluminumacetyl acetonate, chromic acetyl acetonate, zirconium ethoxide, chromicisobutoxide and triethyl aluminum.

In another embodiment, the cations of one or more of such metals arepresent in the absorbent composition at a level of 0.01-5.0milliequivalents of cation per gram of poly-electrolyte, and preferably0.1-1.0 milliequivalents of cation per gram of poly-electrolyte. Lowercation levels do not render the polymeric composition water-insoluble,while higher cation levels render the polymer composition not onlywater-insoluble, but also non-swellable.

The superabsorbent polymer according to the invention can furthercomprise from 0 to about 5 wt % of a multivalent metal salt, based onthe weight of the mixture. In one embodiment, the multivalent metal saltis water-soluble. Examples of metal cations include the cations of Al,Fe, Zr, Mg and Zn. In one embodiment, the metal cation has a valence ofat least +3, with Al being most preferred. Examples of anions in themultivalent metal salt include halides, chlorohydrates, sulfates,nitrates and acetates. In one embodiment, the anions are chlorides,sulfates, chlorohydrates and acetates. In one embodiment, the anions arechlorohydrates and sulfates. Aluminum sulfate is the most preferredmultivalent metal salt and is readily commercially available. In anotherembodiment, the form of aluminum sulfate is hydrated aluminum sulfate,preferably aluminum sulfate having from 12 to 14 waters of hydration.Mixtures of multivalent metal salts can be employed.

In another embodiment, the superabsorbent polymers according to theinvention may further include from o to about 5 wt % of water-insoluble,inorganic powder. The insoluble inorganic powder additive may be asingle compound or a mixture of compounds selected from the above list.

In another embodiment, the superabsorbent polymer according to theinvention may also include the addition of from o to about 5 wt % of asurfactant to the polymer particle surface. It is preferred that thesebe added immediately prior to, during or immediately after the surfacecross-linking step. Examples of such surfactants include anionic,non-ionic, cationic and amphoteric surface active agents, such as fattyacid salts, coco amines and amides and their salts, alkylsulfuric estersalts, alkylbenzene sulfonic acid salts, dialkyl sulfo-succinate, alkylphosphate salt, and polyoxyethylene alkyl sulfate salt; polyoxyethylenealkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene fattyacid ester, sorbitan fatty acid ester, polyoxy sorbitan fatty acidester, polyoxyethylene alkylamine, fatty acid esters, andoxyethylene-oxypropylene block polymer; alkyl amine salts, quaternaryammonium salts; and lauryl dimethylamine oxide. However, it is notnecessary to restrict the surfactant to those mentioned above. Suchsurfactants may be used individually, or in combination.

It is sometimes desirable to employ surface additives that performseveral roles during surface modifications. For example, a singleadditive may be a surfactant, viscosity modifier and react to cross-linkpolymer chains. Surfactants can be very useful in controlling the“Wetting out ” of the rubber when SAP solution is applied in situ.

In another embodiment, the polymerizable compounds may be polymerizableby any type of polymerization reaction, by use of a polymerizationinitiator that is activated, to initiate the polymerization. In oneembodiment herein, the polymerization reaction is a free radicalreaction, and the polymerizable compounds, e.g. monomers, comprisetherefore groups that can form chemical bonds with one another in aradical reaction. Such a free radical polymerization reaction typicallytakes place in the presence of a radical initiator, as described below.Particularly suitable monomers may include an unsaturated group, e.g. aC═C group.

Monomers herein include ethylene oxide; propylene oxide; ethylenimine;but typically olefinically unsaturated carboxylates and/or carboxylicacids, and/or amides or esters thereof, for example, selected acrylicacids typified by acrylic acid itself; methacrylic acid, α-chloroacrylicacid, α-cyanoamylic acid, β-methylacrylic acid (crotonic acid),α-phenylacrylic acid, β-acryloxypropionic acid, sorbic acid,α-chlorosorbic acid, angelic acid, cinnamic acid, p-chlorocinnamic acid,β-stearylacrylic acid, itaconic acid, citroconic acid, mesaconic acid,glutaconic acid, aconitic acid, maleic acid, fumaric acid,tricarboxyethylene, and maleic anhydride; and/or any of the carboxylatesof these polymerizable compounds, e.g. carboxylate salts.

In another embodiment, the polymerizable compounds include or consist ofacrylic acids and/or acrylate salts (and/or precursors thereof, such astypically acrylic esters).

In another embodiment, the anionic group precursors include methoxyethylesters (e.g. acrylic ester), ethoxyethyl esters (e.g. acrylic ester),methyl esters (e.g. acrylic ester), and ethyl esters (e.g. acrylicester).

It should be understood that polymerizable compounds that do not have ananionic, group or precursor, may be used herein. Such compounds caninclude, for example, monomers containing the following types offunctional groups: hydroxyl groups, amino groups, and aryl groups (e.g.,phenyl groups, such as those derived from styrene monomer). Otheroptional polymerizable monomers that may be used in addition includeunsaturated hydrocarbons such as ethylene, propylene, 1-butene,butadiene, and isoprene. These non-acid monomers are well-knownmaterials and are described in greater detail, for example, in U.S. Pat.No. 4,076,663 (Masuda et al.), issued Feb. 28, 1978, and in U.S. Pat.No. 4,062,817 (Westerman), issued Dec. 13, 1977.

In another embodiment, the polymerization rate can be controlled throughthe identity and amount of the initiator system used. As for exampledescribed in US2008/242817, the use of azo compound initiator or redoxinitiators is advantageous for directing the rate of polymerization.

For some initiators, no activation is needed; other initiators mayrequire activation, as known in the art. The initiator may be activatedby any method known in the art, including heat or radiation. Thereto, itmay be desirable that the dispersions/solutions of the monomer compoundand/or clay are cooled (e.g. to a temperature of less thanpolymerization temperature, e.g. less than 20° C., or less than 10° C.)or and/or shielded from radiation prior to introduction of theinitiator, and optionally at the moment of addition of the initiator,and that the combination of initiator and dispersion/solution is exposedto the activation source, e.g. heat, radiation, only at the desiredmoment, for example upon introduction onto the spraying step/sprayingtool or upon introduction into the vessel. In another embodiment, apolymerization catalyst may also be present, such as for example TMEDA,N,N,N′,N′ tetramethylethylenediamine.

In another embodiment, the superabsorbent polymer can comprise from 0 toabout 5 wt. % of a penetration modifier that is added immediatelybefore, during or immediately after the surface cross-linking agent.Examples of penetration modifiers include compounds which alter thepenetration depth of surface-modifying agents in to the superabsorbentpolymer particle, fiber, film, foam or bead by changing the viscosity,surface tension, ionic character or adhesion of the agents or medium inwhich these agents are implied.

In another embodiment, aqueous superabsorbent polymer solution can beblended with polyethylene and extruded into hydrophilic yarn, which canbe then tufted into synthetic turf system. In one embodiment, the coatedinfill achieves the goal of distributing the SAP over as much surfacearea as possible such that the distribution facilitates cooling withoutconcentrated. SAP. The surface area of the total yarn element in thesynthetic turf system is substantial, which would allow a very smallamount of the Aqueous SAP being added as to not diminish the strength ofthe fiber. Therefore, while it is an option in certain embodiments, itis not necessary to have 100% of tli.e yarn act as a SAP carrier. In oneembodiment, at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% ofthe synthetic turf system tufts are composed yarn comprising aqueoussuperabsorbent polymer solution blended with polyethylene and extrudedinto hydrophilic yarn.

In another embodiment, the superabsorbent polymer is suitably preparedby two methods. The polymer can be prepared continuously ordiscontinuously in a large-scale industrial manner by theabove-mentioned known process, the after-cross-linking being carried outaccordingly.

An anionic polymer is intended, to refer to a polymer comprising afunctional group or groups capable of becoming negatively charged ionsupon ionization in an aqueous solution. In general, suitable functionalgroups for an anionic polymer include, but are not limited to, carboxylgroups, sulfonate groups, sulphate groups, sulfite groups, and phosphategroups. Suitably, the functional groups are carboxyl groups. It ispreferred that these functional groups are in neutralized form. Asuitable degree of neutralization is at least 50%, more suitably atleast 80%, and even more suitably at least 100%.

A cationic polymer is intended to refer to a polymer comprising afunctional group or groups capable of becoming positively charged ionsupon ionization in an aqueous solution. In general, suitable functionalgroups for a cationic polymer include, but are not limited to, primary,secondary, or tertiary amino groups, imino groups, imido groups, amidogroups, and quaternary ammonium groups. It is suitable that thesefunctional groups are in neutralized form. A suitable degree ofneutralization is at least 50%, more suitably at. least 60%, and evenmore suitably at least 70%.

Examples of synthetic anionic superabsorbent polymers include the alkalimetal and ammonium salts or partial salts of poly(acrylic acid),poly(methacrylic acid), hydrolyzed poly(acrylamides), maleic anhydridecopolymers with vinyl ethers and alpha-olefins, poly(vinyl acetic acid),poly(vinyl sulfonic acid), poly(vinyl phosphonic acid), poly(vinylethers), poly(vinyl pyrrolidone), poly(vinylmorpholinone), poly(vinylalcohol), and mixtures and copolymers thereof. Examples of natural basedanionic polymers include the salts or partial salts of carboxymethylcellulose, carboxymethyl starch, alginates, and carrageenans. Also,synthetic polypeptides such as polyaspartic acid and polyglutamic acidcan he examples of the anionic polymers. Examples of synthetic cationicsuperabsorbent polymers include the salts or partial salts of poly(vinylamines), poly(allylamines), polyethylene imine), poly(amino proanolvinyl ethers), poly(acrylamidopropyl trimethyl ammonium chloride),poly(diallyldimethyl ammonium chloride). Examples of natural basedcationic polymers include partially deacetalated chitosan and chitosansalts. Also synthetic polypeptides such as polyasparagins, polylysines,polyglutamines, polyarginines can be examples of the cationic polymers.

In some aspects, the present invention may further include post treatingthe superabsorbent polymer composition after surface treatment with upto about 5% by weight of the dry superabsorbent polymer composition,such as from about 0.1 to about. 5% by weight of a cationic polymer. Acationic polymer as used herein refers to a polymer or mixture ofpolymers comprising a functional group or groups having a potential ofbecoming positively charged ions upon ionization in an aqueous solution.Suitable functional groups for a cationic polymer include, but are notlimited to, primary, secondary, or tertiary amino groups, imino groups,imido groups, amido groups, and quaternary ammonium groups. Examples ofsynthetic cationic polymers include the salts or partial salts ofpoly(vinyl amines), poly(allylamines), polyethylene imine), poly(aminopropanol vinyl ethers), poly(acrylamidopropyl trimethyl ammoniumchloride), poly(diallyldimethyl ammonium chloride). Examples of naturalbased cationic polymers include partially deacetylated chitin, chitosanand chitosan salts. Synthetic polypeptides such as polyasparagins,polylysines, polyglutamines, polyarginines are also suitable cationicpolymers.

In one embodiment, performance-enhancing additive(s) are added to thematerial. In one embodiment, the performance-enhancing additive(s) areantimicrobials. In one embodiment, the antimicrobial actives are boroncontaining compounds such as borax pentahydrate, borax decahydrate,boric acid, polyborate, tetraboric acid, sodium metaborate, anhydrous,boron components of polymers, and mixtures thereof.

In one embodiment, the odor absorbing/inhibiting active inhibits theformation of odors. An illustrative material is a water-soluble metalsalt such as silver, copper, zinc, iron, and aluminum salts and mixturesthereof. In another embodiment, the metallic salts are zinc chloride,zinc gluconate, zinc lactate, zinc maleate, zinc salicylate, zincsulfate, zinc ricinoleate, copper chloride, copper gluconate, andmixtures thereof. In another embodiment, the odor control activesinclude nanoparticles that may be composed of many different materialssuch as carbon, metals, metal halides or oxides, or other materials.Additional types of odor absorbing/inhibiting actives includecyclodextrin, zeolites, silicas, activated carbon (also known asactivated charcoal), acidic, salt-forming materials, and mixturesthereof. Activated alumina (Al₂O₃) has been found to provide odorcontrol comparable and even superior to other odor control additivessuch as activated carbon, zeolites, and silica gel. Alumina is a whitegranular material, and is also called aluminum oxide.

In some aspects, additional additives may optionally be employed withthe particulate superabsorbent polymer compositions, includingodor-binding substances, such as cyclodextrins, zeolites, inorganic ororganic salts, and similar materials; anti-caking additives, flowmodification agents, surfactants, viscosity modifiers, and the like. Inaddition, additives may be employed that perform several roles duringmodifications. For example, a single additive may be a surfactant,viscosity modifier, and may react to cross-link polymer chains.

In another embodiment, a color altering agent such as a dye, pigmentedpolymer, metallic paint, bleach, lightener, etc. may be added to varythe color of absorbent particles, such as to darken or lighten the colorof all or parts of the composition so it is more appealing. In anotherembodiment, the color-altering agent comprises up to approximately 20%of the absorbent composition, more preferably, 0.001%-5% of thecomposition. In another embodiment, the color altering agent comprisesapproximately 0.001%-0.1% of the composition.

In another embodiment, the carriers for the color-altering agent arezeolites, carbon, charcoal, etc. These substrates can he dyed, painted,coated with powdered colorant, etc.

In another embodiment, the activated alumina and activated carbon mayinclude an embedded coloring agent that has been added during thefabrication of the activated alumina or activated carbon to form acolored particle.

In composite and other particles, the activated alumina can also beadded in an amount sufficient to lighten or otherwise alter the overallcolor of the particle or the overall color of the entire composition.

Large particles of carbon, e.g., activated carbon or charcoal, can alsobe used as a darkening agent Such particles are preferably within aparticle diameter size range of about 0.01 to 10 times the mean diameterof the other particles in the mixture.

In another embodiment, the core mentioned above can also be consideredan active, for example including a lightweight material in the core toreduce the weight of the particle, a core made of pH-altering material,etc.

(a) Coating of SBR Crumb Rubber

In another embodiment, the largest volume of the infill in mostsynthetic turf systems consists of SBR crumb rubber sourced frompassenger car and small truck tires. The rubber can be either groundunder ambient or cryogenic conditions. The particle size of the rubbercan vary between 6 and 50 mesh. A desirable particle size range is from10 to 20 mesh.

In another embodiment, the amount of SAP in the synthetic turf infillshould be in a range that provides enough water to cool the turf for aminimum time period to encompass a full athletic event or practice time.It is more desirable to have enough water present to cool the turf overa period of several days to reduce the frequency of hydrating the turf.It is also desirable to keep the SAP content below the level that willchange the athletic performance of the synthetic turf surface. The rangeof SAP levels in the turf should be in the range of 2 grams/sq. ft. to40 grams/sq. ft. A more desirable range is between 4 and 20 grams/sq ft.An even more desirable range is from 6 to 10 grams/sq ft.

Applying the SAP as a thin coat on all or part of the SBR particlesurface provides the most even distribution of the SAP within the turfinfill. Most superabsorbent polymers are insoluble and cannot heintroduced as a solution for coating the rubber particles. In anotherembodiment, the coating process can be accomplished by coating therubber particles with a water solution of a low molecular weight SAP andthen cross-linking the low molecular weight polymer chains to form aninsoluble polymer coating on the rubber particles. A low molecularweight water-soluble polymer of acrylic acid can be partiallyneutralized with ammonium hydroxide to provide reactive sites forcross-linking on the prepolymer. In another embodiment, thecross-linking agent is ammonium zirconium carbonate containinghydroxylated zirconium polymers. In another embodiment, thecross-linking reaction takes place at temperatures between 0 and 70° C.Evaporation of the water drives the reaction to completion forming aninsoluble high molecular weight polymer coating.

In another embodiment, the coating of the rubber particles with thereactive solution can be accomplished by any means that distributes thewater solution evenly over the rubber particle. In another embodiment,the formulated SBR used in tires can have a hydrophobic characteristicthat causes the water to be isolated as droplets across the particlesurface. SAP coatings made with isolated droplets of reactive polymersolution will have thicker, deposits of SAP that can have less physicalintegrity than a more evenly distributed film of SAP. In anotherembodiment, a more uniform film coating is provided by introducing asurfactant into the water solution to reduce the surface tension betweenthe SBR surface and the water solution. In another embodiment, thesurfactant can be anionic, cationic, or non-ionic in nature.

It is also desirable to have SAP that retains physical integrity in thehydrated state. This prevents abrasion of the SAP during athleticactivity on the synthetic turf. In another embodiment, the physicalintegrity can be introduced by having a range of 5 to 30% of the acidsites on the polyacrylic acid cross-linked. In another embodiment, thedesirable range is 10 to 20% cross-link. density.

The physical integrity of the SAP coating and the adhesion of thecoating to the SBR surface can be increased by incorporating a bindermolecule into the SAP formulation. In another embodiment, the binder hasa styrenic portion that is compatible with the styrene butadiene tirerubber. In another embodiment, the binder should also have hydroxyl orcarboxyl groups that can react with the zirconium carbonatecross-linker. In another embodiment, the binder can be used in a rangeof to 50 weight percent based on the amount of SAP weight. In anotherembodiment, the binder can be mixed with the polymer and cross-linkersolution or it can be added as a pre-coat on the SBR particle prior tointroduction of the prepolymer/cross-linker solution.

(b) Coating of Sand infill

Silica sand is used in the majority of 3^(rd) generation synthetic turfsystems as a ballast to hold the turf in place and to adjust thefirmness of the infill mixture to optimize the athletic performance ofthe turf system. In another embodiment, the sand as well as the rubbercan be used as a carrier to introduce the SAP into the turf system. Asin the case of the rubber infill, the SAP can be most advantageouslyintroduced as a thin coating of SAP on the sand particles.

The same method of coating the sand particle with a water solution of apre-polymer of polyacrylic acid with a cross-linker can be used to coatthe silica sand. The water solution is blended with the sand to wet outthe surface of the sand. The water is allowed to evaporate and drive thecross-linking reaction.

The integrity of the SAP and the adhesion of the SAP to the sandparticle surface can be enhanced by using a binder. The binder shouldcontain silane groups that will have affinity for the silica sandsurface as well as hydroxyl or carboxyl groups to react with thetitanium carbonate cross-linker.

(c) Introduction of the SAP Coated Sand and/or Rubber into the TurfSystem

The hydrated SAP releases water when the turf system is heated bysunlight. Higher levels of infrared heat in the sunlight releases morewater, which in turn provides more cooling to the turf surface. Toprovide cooling, the SAP must be hydrated and must be located in thesystem where the heat energy impinging on the turf surface from thesunlight can be effectively transmitted to the hydrated SAP. SAP that isinsulated from the sunlight will likely be ineffective at providingcooling to the surface.

The SAP coated rubber or sand can be introduced to the field in the samemanner that is used to introduce normal rubber and sand to the infill.The coated infill can be added using a broadcast spreader followed bybrushing of the turf to distribute the infill within the synthetic turfgrass blades. The sand and rubber can be pre-mixed, mixed in situ byadding the rubber and sand in layers and brushing the turf to mix thelayers together. Alternatively, the sand and rubber can be introduced asdiscrete layers with the sand on bottom and rubber on top.

(d) Infill Particles

As mentioned above, having the water-absorption material coatedparticles 100 near the surface enhances the effectiveness of the waterrelease. This can be accomplished, by putting the SAP coated rubberparticles or crumbs or coated rubber and sand mixture in the top layerof the infill and all of the uncoated rubber and rubber/sand mix in thebottom of the infill layer.

To prevent mixing of the coated and non-coated rubber, the rubber usedfor the coated infill can have a larger particle size than the remainderof the rubber particles. The preferred particle size range for the SAPcoated particles is 10-16 mesh. The preferred particle size range forthe uncoated rubber particles used in the bottom layer of infill is18-30 mesh.

For the coated sand to be effective for evaporative cooling, it shouldhe in the top layer of the infill. The higher specific gravity androunder particle shape of standard sand compared to the SBR rubber usedin turf infill causes the sand to migrate to the bottom of the turfduring athletic activity and grooming of the athletic field. The SAPcoated sand will have lower specific gravity than the uncoated sand. Theparticle size of the SAP coated sand can also be adjusted to have afinal particle size similar in size or slightly smaller than the rubberin the top layer of the infill.

(e) Spraying of SAP Solution

The pre-coating of SAP rubber or SAP sand requires the manufacturingsteps of coating and drying the infill prior to shipping to the fieldfor installation. The coated materials must also be protected fromrainfall during shipping and storage onsite before being installed inthe field. It is advantageous to avoid the pre-coating step byintroducing the SAP rubber and/or SAP sand by applying the SAP as asolution to the infill while the infill is being installed. The bottomlayer of the infill can be installed without any SAP allowing the SAP tobe added to the upper layer of infill as the infill is installed.

The aqueous solution of prepolymer, cross-linker, and binder can besprayed between lifts of rubber or between lifts of rubber and sand. TheSAP solution can be introduced as a spray above the turf surface or itcan be introduced below the surface of the infill Introducing thesolution under the surface has the advantage of not introducing SAPsolution to the grass fibers that are exposed above the turf surface.Introducing the SAP solution as a spray above the turf has the advantageof introducing the SAP with an even distribution across the surface ofthe turf. The SAP can be introduced at a spray rate combined with theconcentration of the water-soluble SAP to yield, an amount of SAP in thefinal turf of 2 to 40 grams of SAP per square foot of turf. Thepreferred amount of SAP introduced per square foot of turf is from 6 to10 grams.

The SAP can be introduced in from one to 10 layers. The more layersallow the SAP to be introduced more evenly. The SAP solution can beintroduced between layers of infill. When the field is brushed to evenlydistribute the infill, the SAP distribution evenness is also increased.

(f) Spraying of Installed Fields

In another embodiment of the invention, fields installed with standardparticulates as described above (particularly rubber or rubber/sandmixtures) can be converted to SAP cooled fields by introducing SAPsolution into the installed infill. In another embodiment of theinvention, fields installed with SAP coated rubber or sand that has lostits effectiveness for cooling can also be reactivated by introducingadditional SAP solution. The SAP solution can be introduced by sprayingor by injecting the SAP solution into the top layer of the infill. TheSAP solution can be introduced into fields during a grooming procedureto distribute the SAP within the infill or the top layer of infill canbe removed and reintroduced in layers with the SAP solution addedbetween layers of infill. The SAP solution can also be introducedsubstantially concurrent with installation of the infill by spraying theinfill particles with the SAP solution as it is being installed as aninfill layer.

3. Multi-Layer Cooling Mat

In another embodiment of the invention, an unproved artificial turfsystem is described along with a method for constructing a system thatreduces temperature, resists compaction, minimizes abrasiveness and thatprovide superior shock impact resistance and stability in comparison toconventional artificial turf systems.

In one embodiment, the invention comprises fabricating a recreationalsurface using a mixture comprising resilient and inelastic particles andparticles of a rubber coated granular material. In one embodiment, themixture includes a relative proportion of the resilient particles withrespect to the inelastic particles in order to adjust the parameters ofthe surface.

In an alternative embodiment of the invention that is depicted above andin FIGS. 1-3, the synthetic turf system may further comprise a coolingmat (infill) 40, which may be comprised of one or more layers. When morethan one layer comprises the cooling mat, each layer of the cooling matmay be of different compositions than other layers. In one embodiment,at least one of the layers is comprised of a core particle coated with awater-absorbing material. In one embodiment, the water-absorbingmaterial is a super absorbent polymer.

In one embodiment, at least one of the layers is comprised of a layer ofshock absorbing material. In one embodiment., the layer of shockabsorbing material is comprised of synthetic rubber.

In one embodiment, the layer of shock absorbing material has a thicknessthat is substantially within the range of about 10 mm to about 60 mm andmore preferably within a range of about 15 mm to about 40 mm.

In another embodiment, the turf system further comprises a shock padsystem.

In one embodiment, the synthetic turf system further comprises a shockpad or E-layer. In one embodiment, the shock pad is applied below thebacking layer. There are two general forms of shock pads used insynthetic turf systems. One is an in situ system that is fabricated onsite as the turf is installed. The other type is prefabricated andbrought to the field to be installed with the turf.

In one embodiment, a shock pad or e-layer may be applied to increase thevalue of shock absorption and vertical deformation. In one embodiment,the amount of infill material can than be decreased.

In one embodiment, after the manufacturing of the synthetic turf fabric,a shock pad may be glued to or loosely laid upon a resilient pad. In oneembodiment, the resilient pad is an elastomeric pad, for example,E-Layer Shock pad. In one embodiment, the pad is from about 1 mm toabout 50 mm thick. In another embodiment., the pad is from about 10 mmto about 40 mm thick. In another embodiment, the pad is from about 15 mmto about 35 mm thick. The resilience from the pad provides safer shockabsorption levels.

In one embodiment, surface coverings for sporting use are constructed bystitching into a preformed fabric backing layer to form tufts, and thenbonding the primary backing layer to an impact-absorbing resilient lowerlayer or shock pad.

In one embodiment, the layers are chemically as well as physicallyjoined together to form an integrated shock pad capable ofmultidirectional movement, similar to natural turf.

In one embodiment, the in situ pads are also called elastic layers(e-layers). They are a combination of SBR crumb rubber and apolyurethane binder. The two components are mixed to form a consistencysimilar to asphalt. The material is installed using a paving machine.The material under the e-layer may be asphalt, concrete, or compactedstone. The e-layers are paved with thickness of 15 to 30 mm. Anythingover 20 mm is installed in two layers. One or all layers may containsome small pebble stone to increase the firmness of the e-layer.

In one embodiment, the prefabricated pads comprise an e-layer preparedas a large billet and a 8 to 12 mm thick pad is skived off the outsideof the billet. In one embodiment, the material is then rolled and takento the field and installed in 4 foot widths.

In another embodiment, the pad comprises one or more types of closedcell or open cell foams. In one embodiment, these are prepared as rollsor sheets that are connected to each other on the field base prior tothe turf being installed. In one embodiment, the pads can be from 5 to50 mm thickness depending on the density and material from which thepads are made. In another embodiment, the pads can be from 10 to 40 mmthickness. In another embodiment, the pads can be from 15 to 35 mmthickness.

In one embodiment, the infill 50 includes both resilient particles andparticles of inelastic granular material. A resilient particle isdefined as a particle that is fabricated from a material or materialsthat are substantially compressible at pressures that will be appliedthereto when a person is walking or running on an artificial turfinstallation. A resilient particle in the preferred embodiment of theinvention is embodied as a rubber particle but could alternatively befabricated, from another resilient material such as cork or vermiculate.

The material from which the rubber particles and/or the particles 100 ofwater-absorbing material coated granular material is fabricated may beimpregnated with a substance that inhibits the growth of bacteria and/ormold. Alternatively, a coating of such a substance may be applied to theexternal surface of the rubber particle and/or to the external surfaceof the particles 100 of water-absorbing material coated granularmaterial.

Referring now to FIG. 6, artificial turf assembly 10 according to afirst embodiment of the invention includes a pile fabric having abacking 30. Artificial turf assembly 10 also preferably includes aninfill 50, which is preferably a substantially homogeneous mixture ofcoated particles 100 comprising water-absorbing material coated granularmaterial and rubber particles. In one embodiment, the rubber particlesand the particles 100 are sized to have outer diameters that aresubstantially the same. In one embodiment, the material that is used inthe particles 100 is a different material than the rubber material thatis used to fabricate the rubber particles, with the material that isused to fabricate the rubber particles preferably having a greaterweight density than the material that is used to fabricate the particles100 comprising granular material coated with water-absorbing material.

In a recreational surface according to a second embodiment of theinvention, a pile fabric as described above with reference to the firstembodiment is installed. An infill 50 is then installed in separate anddistinct layers. In another embodiment, this is performed by firstinstalling a first (bottom) infill layer 60 that comprises granularmaterial, rubber particles or a mixture thereof.

After installation of the first (bottom) infill layer 60, a second (top)infill layer 70 is installed directly on top of the first (bottom)infill layer 60, as seen in FIG. 7. The second infill layer 70 comprisesa granular material, rubber particles or a mixture thereof wherein atleast a portion of the infill particles are coated with SAP. In oneembodiment, the coated infill particles of the second (top) infill layer70 comprise at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or100% of the total infill particle mix.

In another embodiment, one or more third (middle) infill layers 80 areinstalled directly on top of the first (bottom) infill layer 6o butbefore addition of the second (top) infill layer 70, which is theninstalled directly on top of the one or more third (middle) infilllayers 80. The infill may further comprise one or more additional layers90 as dictated by performance requirements.

While this invention has been described in conjunction with the specificembodiments outlined above, it is evident, that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, the preferred embodiments of the invention as setforth above are intended to be illustrative, not limiting. Variouschanges may be made without departing from the spirit, and scope of theinvention.

1. A synthetic turf infill cooling granule comprising a core particlecoated with a water-absorbing material, wherein the water-absorbingmaterial is a super absorbent polymer and wherein the core particlecomprises a granular material selected from the group consisting ofstone, gravel, sand, asphalt, cement, ceramic beads, soil, clay, shale,slate, diatomaceous earth, perlite, silica, organic minerals, rubber orcombinations thereof.
 2. The synthetic turf infill cooling granule ofclaim 1, wherein the core particle comprises an inelastic material. 3.The synthetic turf infill cooling granule of claim 2, wherein the coreparticle is configured to be have a physical properly selected from thegroup consisting of solid, hollow, absorbent, nonabsorbent, andcombinations thereof.
 4. The synthetic turf infill cooling granule ofclaim 2, wherein the inelastic material is selected from the groupconsisting of metallic material, a ceramic material, a stone material, amineral material, a hard plastic material and mixtures thereof.
 5. Thesynthetic turf infill cooling granule of claim 2, wherein the coreparticle comprises a granular material is an inorganic mineral selectedfrom the group consisting of bentonite, zeolite, montmorillonite,diatomaceous earth, opaline silica, crystalline silica, silica gel,Georgia White clay, sepiolite, calcite, dolomite, slate, pumice,tobermite, marls, attapulgite, kaolinite, halloysite, smectite,hectorite, Fuller's earth, fossilized plant materials, expanded perlite,gypsum, and mixtures thereof.
 6. The synthetic turf infill coolinggranule of claim 3, wherein the core particle comprises a particle ofsand.
 7. The synthetic turf infill cooling granule of claim 1, whereinthe core particle comprises a resilient material.
 8. The synthetic turfinfill cooling granule of claim 7, wherein the resilient material isselected from the group consisting of an elastomeric particle, a corkparticle, a vermiculate particle and mixtures thereof.
 9. The syntheticturf infill cooling granule of claim 7, wherein the resilient materialcomprises elastomeric material selected from the group consisting ofethylene-propylene-diene monomer (EPDM) rubber, nitrile rubber, nitrileacrylonitrile butadiene rubber (NBR), carboxylated acrylonitrilebutadiene rubber (XNBR), hydrogenated acrylonitrile butadiene rubber(HNBR), carboxylated hydrogenated acrylonitrile butadiene rubber(XHNBR), hydrogenated carboxylated acrylonitrile butadiene rubber(HXNBR), ethylene propylene (EPR), tetrafluoroethylene and propylenemonomer (FEPM) elastomers, fluoroelastomers (FKM), perfluoroelastomers(FEKM), ethylenically unsaturated nitrile-conjugated diene-based highsaturation copolymer rubber, epoxylated natural rubber, nitrilebutadiene rubber, hydrin rubber, acryl rubber, maleic anhydride graftedacrylonitrile-butadiene-styrene rubber, maleic anhydride graftedethylene-propylene-diene rubber, maleic anhydride graftedstyrene-ethylene/butadiene-styrene rubber, maleated ethylene-propylenecopolymer rubber, maleated ethylene-butene rubber, maleatedethylene-hexene rubber, maleated ethylene-octene rubber, maleatedethylene-decene rubber, maleated ethylene-vinyl acetate copolymer,maleated ethylene-methyl acrylate copolymer, maleated ethylene-ethylacrylate copolymer, maleated ethylene-acrylic acid copolymer,EPDM/styrene copolymer, maleic acid modified EPDM/styrene copolymer,EPDM/acrylonitrile graft copolymer, maleic acid modifiedEPDM/acrylonitrile graft copolymer, styrene/maleic acid copolymer,reactive phenoxy thermoplastic resins, maleated isobutylene-isoprenecopolymer, maleated isobutylene-paramethylstyrene copolymer, maleatedhalogenated isobutylene-isoprene copolymer, maleated star branched butyl(SBB) copolymer, maleated BIMS copolymer, and mixtures thereof.
 10. Thesynthetic turf infill cooling granule of claim 7, wherein the resilientmaterial comprises at least one elastomer.
 11. The synthetic turf infillcooling granule of claim 7, wherein the resilient material comprises atleast one thermoplastic elastomer selected from the group consisting ofstyrenic block copolymers, thermoplastic polyolefins, thermoplasticvulcanisates, thermoplastic polyurethanes, thermoplastic copolyesters,melt processable rubber and thermoplastic polyether block amides. 12.The synthetic turf infill cooling granule of claim 7, wherein theresilient material comprises granulized rubber.
 13. The synthetic turfinfill cooling granule of claim 1, wherein the average granule sizeranges from about 0.2 mm to about 6 mm in diameter.
 14. The syntheticturf infill cooling granule of claim 1, wherein the average thickness ofthe superabsorbent polymer coating is from about 1 to about 1000 μm. 15.The synthetic turf infill cooling granule of claim 1, wherein theaverage thickness of the superabsorbent polymer coating is from about 5μm to about 500 μm.
 16. The synthetic turf infill cooling granule ofclaim 15, wherein the water-absorbing material coated granular materialare fabricated so that the water-absorbing material coating comprisesabout 0.2% to about 10% by weight of the core granular material.
 17. Thesynthetic turf infill cooling granule of claim 16, wherein thesuperabsorbent polymer comprises one or more water-swellable,superabsorbent polymer compositions capable, under the most favorableconditions, of absorbing at least about 1 times their weight of anaqueous solution.
 18. The synthetic turf infill cooling granule of claim17, wherein the superabsorbent polymer comprises at least one normallywater-soluble polymer which has been cross-linked to render itsubstantially water insoluble, but capable of absorbing water.
 19. Thesynthetic turf infill cooling granule of claim 17, wherein thesuperabsorbent polymer comprises at least one polymer selected from thegroup consisting of starch graft copolymers, cross-linkedcarboxymethylcellulose derivatives modified hydrophilic polyacrylatesand mixtures thereof.
 20. The synthetic turf infill cooling granule ofclaim 17, wherein the superabsorbent polymer comprises at least onepolymer selected from the group consisting of hydrolyzed starch-acrylategraft co-polymer, saponified acrylic acid ester-vinyl co-polymer,neutralized cross-linked polyacrylic acid, cross-linked polyacrylatesalt, and carboxylated cellulose.
 21. The synthetic turf infill coolinggranule of claim 17, wherein the superabsorbent polymer comprises atleast one acrylate polymers selected from the group consisting ofacrylic acid, methacrylic acid, acrylate, methyl acrylate, ethylacrylate, methyl methacrylate, ethyl methacrylate, a dialkylaminoalkylacrylate, a dialkylaminoalkyl methacrylate, a trialkylammonioalkylacrylate, a trialkylammonioalkyl methacrylate, polymers and copolymersof acrylic acid, methacrylic acid, methyl methacrylate, ethylmethacrylate, 2-dimethylaminoethyl methacrylate, andtrimethylammonioethyl methacrylate chloride and mixtures thereof. 22.The synthetic turf infill cooling granule of claim 1, further comprisingone or more binders, wherein the one or more binders coat at least aportion of the core particle.
 23. The synthetic turf infill coolinggranule of claim 22, wherein the binder is characterized by having animproved adherence to the surface of the core particle as well as to thewater absorbing material as compared to the adherence between the waterabsorbing material and the core particle when being in direct contact.24. The synthetic turf infill cooling granule of claim 23, wherein oneor more binders are incorporated into the SAP water absorbing material.25. The synthetic turf infill cooling granule of claim 23, wherein thebinding agent is a silane.
 26. The synthetic turf infill cooling granuleof claim 23, wherein the silane is one or more agents selected form thegroup consisting of organosilozane, silane monomer, or mixtures thereof.27. A process for the preparation of polymer granules according to claimcomprising: introducing a solution of one or more non-cross-linkedacrylic polymers and one or more cross-linking agents, wherein thesoluble polymer is one or more partially neutralized polyacryclic acidshaving between 60% and 90% of the acid groups neutralized and whereinthe crosslinking agent is a polyvalent cation selected from the groupconsisting of aluminum, titanium, and zirconium and wherein the crosslinking renders the polymer insoluble and attached to infill granule.28. The process of claim 26 further comprising the addition of asurfactant capable of wetting out the core particle for more evendistribution of the polymer on the core particle, wherein the surfactantis an anionic, cationic, non-ionic, or amphoteric.
 29. The process ofclaim 27 wherein the surfactant is added at a level between 0.1 and 5%of the weight of the core particle.
 30. The process of claim 28 whereinthe surfactant is added at a level between 0.5 and 2% of the weight ofthe core particle.
 31. An artificial turf infill comprising the infillcooling granules of claim 1 wherein the core particles are selected fromthe group consisting of uncoated resilient and inelastic particles andmixtures thereof.
 32. An artificial grass turf system, the artificialturf comprising a backing layer with a plurality of grass-like filamentsattached and an infill material comprising the cooling granules of claim1, wherein the infill is designed to occupy at least some of the spacebetween the grass-like filaments of the artificial turf.
 33. Anartificial grass turf system of claim 31, wherein the turf furthercomprises a foundation, wherein the foundation is selected from one ormore of bare ground, stone, gravel, sand, asphalt, cement, shock pad andrubber.
 34. An artificial grass turf system according to claim 31,wherein the infill layer has a thickness between about 5 and about 60millimeters.
 35. An artificial grass turf system according to claim 33,wherein the infill layer is applied to a level greater than about 10% ofan average height of the grass-like filaments to about 90% of theaverage height of the grass-like filaments.
 36. An artificial grass turfsystem according to claim 34, wherein the infill layer comprises amixture of resilient and inelastic cooling granules.
 37. An artificialgrass turf system according to claim 35, wherein the proportion of theresilient and inelastic cooling granules is selecting according to thedesired physical properties of the covering.
 38. An artificial grassturf system according to claim 35, wherein the infill comprises at leasttwo layers of infill material, the at least two layers having differentcompositions, and wherein at least one of the layers is specified ascontaining a proportion of infill cooling granules of claim
 1. 39. Anartificial grass turf system according to claim 35, wherein the infilllayer comprises a first infill layer on the backing, the first infilllayer predominantly comprising granular material, rubber particles or amixture thereof; and a second infill layer placed substantially over thefirst infill layer, the second infill layer predominantly comprising agranular material, rubber particles or a mixture thereof wherein atleast a portion of the second infill layer particles are the syntheticturf infill cooling granules of claim
 1. 40. An artificial grass turfsystem according to claim 35, wherein the second infill layer comprisescomprise at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%of the total infill particle mix.
 41. An artificial grass turf systemaccording to claim 35, wherein the infill layer further comprises one ormore third infill layers, wherein the one or more third infill layersare installed substantially on top of the first infill layer, andwherein the second infill layer is then installed substantially on topof the one or more third infill layers.
 42. An artificial grass turfsystem according to claim 41, wherein one or more third infill layersconsists essentially of cooling particles predominantly fabricated fromone of either resilient or inelastic core particles.
 43. The artificialturf infill as recited in claim 35 wherein the super absorbent materialis polyacrylamide or polyacrylate.
 44. The artificial turf infill asrecited in claim 35 wherein the infill further comprises sand, rubbergranules, ceramic beads, soil or combinations thereof.
 45. Theartificial turf infill as recited in claim 35 wherein the infill furthercomprises one or more performance-enhancing additive.
 46. The artificialturf infill as recited in claim 45 wherein the one or moreperformance-enhancing additive is selected from the group consisting ofantimicrobial, an odor reducing material, a binder, a fragrance, a coloraltering agent, a dust reducing agent, a nonstick release agent, asuperabsorbent material, cyclodextrin, zeolite, activated carbon, a pHaltering agent, a UV stabilizer, a salt forming material, a ricinoleate,silica gel, crystalline silica, activated alumina, an anti-clumpingagent, and mixtures thereof.
 47. A method of using the polymer granulesaccording to claim 46 as infill material in football fields, soccerfields, hockey fields, rugby fields, tennis fields, for recreation andplaying area's or for athletics tracks.
 48. A process for producing anartificial grass turf system wherein the infill particles are coated insitu by spraying the particles with a solution of a water solublesuperabsorbent polymer and a cross linking agent with the polymerbecoming an insoluble coating on the infill particles as the waterevaporates.
 49. A process as in 48 where the infill is first treatedwith a binder solution and at least partially dried before the SAP andcross-linking agent are added.
 50. A process as in 48 where a dryingstep is added between the addition of the binder solution and theaddition of the polymer solution.
 51. A process as in 48 Where a dryingstep is added after the addition of the SAP and cross linking agent. 52.A process as in 48 there the binder solution and the polymer solutionare added below the surface of the infill layer.